Hinged Component, And Mechanical System Comprising Such A Component

ABSTRACT

A hinged component with one degree of freedom includes at least two concentric rings, movable in rotation in relation to one another around a central axis, defining a friction interface therebetween and including: an outer ring having an inner friction surface and an inner ring having an outer friction surface and an inner friction surface intended to receive a movable member guided by the component in rotation, oscillation and/or translation.

TECHNICAL FIELD

The present invention relates to a hinged component, comprising at leasttwo concentric rings, movable in relation to one another and defining africtional interface therebetween. The invention also concerns amechanical system comprising such a component.

The field of the invention is that of guiding members providing aguiding function in translation or in rotation, in a continuous orreciprocating motion.

PRIOR ART

Conventionally, such a guiding member comprises a ring, designed formounting with the capability to articulate and/or displace an elementsuch as an axle or a shaft.

In practice, such mechanical systems are submitted to significantoperational stresses: high pressure, corrosion, abrasion, shock. Toimprove the service life thereof, lubrication is provided for betweenthe ring and the axle.

The ring can be provided with arrangements serving as a greasereservoir, as described for example within the documents EP0987456,WO2014091123 and WO2014091124 in the name of the Applicant.

When the mechanical system is in operation, the grease gradually emergesfrom arrangements in order to lubricate the friction interface betweenthe ring and the axle. Thus, the arrangements make it possible toimplement lubrication during assembly only, or alternatively with longintervals of lubrication.

The Applicant has great expertise in the field of guiding members, andcontinually seeks to improve existing systems.

DESCRIPTION OF THE INVENTION

The purpose of the present invention is to provide an hinged component,in particular with excellent resistance to wear and seizure, and animproved service life.

To this end, the present invention relates to an hinged component withone degree of freedom, comprising at least two concentric rings, movablein rotation in relation to one another around a central axle, defining afriction interface therebetween and including: an outer ring having aninner friction surface and an inner ring having an outer frictionsurface and an inner friction surface intended to receive a movablemember guided by the component in rotation, oscillation and/ortranslation.

Thus, the invention makes it possible to provide a component that isresistant, compact and simple to implement. The component has animproved service life, as compared to a component which is composed of asingle ring, and which has similar dimensions and volume.

The component has three friction surfaces forming three wear surfaces.In comparison with a component consisting of a single ring having asingle internal friction surface, the service life of the componentaccording to the invention should be multiplied by three. Surprisingly,experiments revealed that the service life thereof was multiplied by atleast five.

In the case of a single articulating ring, the wear is typicallylocalized over an angular sector extending over ⅓ of the circumference.In the case of the invention, the inner ring rotates in relation to theouter ring, which greatly increases the potential wear surface, andtherefore the service life of the component.

In practice, it can be seen that the friction interface between the tworings takes priority. The opposing friction surfaces perform thefunction of main wear surfaces. When this interface is seized, the innerfriction surface of the inner ring takes over as a wear surface.

Advantageously, the component has three friction surfaces that may beprovided with a surface treatment or coating and/or arrangements capableof serving as a reserve of lubricant. Thus, the invention providesgreater control in the design of the component, making it possible toadapt the wear resistance thereof to every application.

According to other advantageous features of the invention, consideredalone or in combination:

-   -   The friction surfaces delimiting the friction interface are        cylindrical.    -   The friction surfaces delimiting the friction interface are        slightly curved. The absolute bend radius of each friction        surface is strictly greater than the radius of the friction        interface under consideration.    -   The friction interface between the rings receives a lubricant.        The component comprises sealing means designed to prevent        leakages of lubricant from the friction interface.    -   The lubricant is grease.    -   The component comprises side elements limiting the axial and        angular movement of the inner ring in relation to the outer        ring.    -   The sealing means comprise a flange on a first side of the        friction interface, and a shoulder on a second side of the        friction interface.    -   The sealing means comprise a flange on each side of the friction        interface.    -   The sealing means comprise a washer interposed between the inner        ring on the one hand, and the flange or shoulder on the other        hand, on each side of the friction interface.    -   The washer is in PTFE.    -   At least one of the friction surfaces comprises a surface        treatment or coating with physical properties different from a        base material of the ring.    -   The surface treatment or coating is multilayer or monolayer.    -   The coating is produced by means of physical vapor deposition        (PVD).    -   The coating is produced by means of chemical vapor deposition        (CVD).    -   The coating is produced by means of thermal spraying.    -   The coating is produced by means of cold spraying.    -   The coating is sprayed in powder form.    -   The coating is sprayed in the form of drops.    -   The coating is produced by means of thermal spraying a high        velocity oxy fuel (HVOF).    -   The coating is produced by means of laser cladding.    -   The coating is anti-seizing.    -   The coating comprises an outer layer of DLC (“diamond-like        carbon”) type amorphous carbon, in particular with a thickness        of between 1 and 5 μm, for example 3 μm.    -   The coating comprises an outer layer of a self-lubricating        composite, in particular based upon resin and/or woven or        non-woven reinforcing, comprising for example PTFE, MoS2 or        graphite type fillers.    -   The coating comprises a polymer lacquer.    -   The treatment is nitriding, and the friction surface has a        compound layer (oxide coating) having a thickness in particular        of between 5 and 50 μm for example 20 μm.    -   The treatment is a hardening over a thickness of between 0.5 and        4 mm, for example 2 mm.    -   At least one of the friction surfaces comprises arrangements        capable of serving as a reserve of lubricant.    -   The arrangements comprise cavities of a circular or alveolar        section.    -   The cavities are macro-cavities, each having a diameter of        between 2 and 15 mm, for example 6 mm.    -   The cavities are microcavities, each having a greater length of        between 15 and 100 μm, and a depth of between 50 nm and 100 μm.    -   The arrangements comprise circular or helical grooves.    -   The arrangements comprise a grid.    -   The arrangements comprise chevrons.    -   The same surface may comprise arrangements of several different        types, or of only one type.    -   The arrangements have a surface density of between 5 and 65%,        the surface density being defined as the ratio between the total        area covered by the arrangements and the total area of said area        including these arrangements.    -   Each friction surface comprises a surface treatment or coating        having physical properties different from a base material of the        ring and/or arrangements capable of serving as a reserve of        lubricant.    -   At least one of the friction surfaces comprises simultaneously a        surface treatment or coating having physical properties        different from a base material of the ring and arrangements        capable of serving as a reserve of lubricant.    -   The outer ring and/or the inner ring is metallic, for example in        steel, cast iron, aluminum, copper alloy, etc.    -   The outer ring and/or the inner ring is of a composite material.    -   The component exclusively comprises two concentric rings, the        friction interface being defined directly between the inner        friction surface of the outer ring and the outer friction        surface of the inner ring.    -   The hinged component comprises at least three concentric rings.    -   The hinged component comprises three rings, with a single        friction interface defined between the three rings. In other        words, two rings are attached to one another, for example by        means of bonding, welding or any other technique.    -   The intermediate ring is self-lubricating. More specifically,        the outer friction surface and/or the inner friction surface of        the intermediate ring is self-lubricating.    -   The intermediate ring comprises a winding of fabric strips and a        resin comprising fillers, mixed in such a way as to implement a        homogeneous product, the strips being crossed over several        layers by means of filament winding.    -   The hinged component comprises three rings, with a friction        interface defined between each pair of rings. In other words,        the three rings are movable in relation to one another.    -   The intermediate ring is metallic.    -   The intermediate ring is made from a composite material.    -   The hinged component comprises four or more rings.

The invention also relates to a mechanical system, comprising a hingedcomponent as mentioned above, and a movable member guided by thecomponent in rotation, oscillation and/or translation.

The mechanical system comprises four friction surfaces, namely the outersurface of the axle, and the three surfaces of the hinged component. Incomparison with an axle mounted within one ring, the service life of themechanical system is greatly improved.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood upon reading the followingdescription, given solely as a non-limiting example, and made withreference to the accompanying figures wherein:

FIG. 1 is an exploded perspective view of a mechanical system accordingto the invention, comprising an axle and a hinged component consistingof two rings and sealing means;

FIG. 2 is a side view of the component of FIG. 1;

FIG. 3 is a perspective view of the component of FIG. 1;

FIG. 4 is a cross-section along line IV-IV in FIG. 2;

FIG. 5 is a larger scale view of the detail V in FIG. 4;

FIG. 6 is an exploded perspective view of another mechanical systemaccording to the invention, comprising an axle and a variant of thehinged component;

FIGS. 7 to 10 are views that are similar to FIGS. 2 to 5 for thecomponent of FIG. 6;

FIGS. 11 and 12 are views that are similar to FIGS. 4 and 5, for anothervariant of the component, comprising three rings defining two frictioninterfaces therebetween; and

FIGS. 13 and 14 are views that are similar to FIGS. 4 and 5, for anothervariant of the component, comprising three rings defining a singlefriction interface therebetween.

DETAILED DESCRIPTION OF THE INVENTION

In FIGS. 1 to 5 a mechanical system is shown according to the invention,comprising a hinged component 1 also according to the invention, and anaxle 2 mounted within the component 1. The axle 2 is guided by thehinged component 1, in rotation (pivoting in one direction, usually overseveral revolutions), oscillation (pivoting in two alternate directions,generally over a portion of a turn) and/or translation (movement in theaxial direction).

The hinged component 1 comprises two concentric rings 10 and 20, movablein rotation in relation to one another around a central axis X1. The tworings 10 and 20 define therebetween a friction interface 40 receiving alubricant L, preferably grease.

The two rings 10 and 20 include an outer ring 10 and an inner ring 20.The outer ring 10 has an inner cylindrical friction surface 12, and anouter cylindrical bearing surface 14. The inner ring 20 has an outercylindrical friction surface 22, and an inner cylindrical frictionsurface 24.

The surfaces 12 and 22 define the friction interface 40 therebetween,radially to the central axis X1. The surface 14 is provided for themounting of the outer ring 10 within a borehole. A channel 42 isarranged radially through the ring 10 between the surfaces 12 and 14, inorder to lubricate the interface 40. The surface 24 is provided forreceiving the axle 2, more precisely the outer cylindrical surface 4 ofthe axle 2. Thus, the axle 2 is guided by the component 1 in rotation,oscillation and/or translation.

The component 1 comprises sealing means 60 designed to prevent leakagesof lubricant L from the friction interface 40. The component 1 thusconstitutes a sealed lubricated structure. The relative rotation betweenthe rings 10 and 20 is greatly facilitated, and the risk of seizing isreduced.

The sealing means 60 comprise lateral members 62, 64, 66 and 68 limitingthe axial displacement of the inner ring 20 in relation to the outerring 10. More specifically, the sealing means 60 comprise a flange 62and a washer 66 on a first side of the interface 40, and a shoulder 64and a washer 68 on a second side of the friction interface 40. Theelements 62, 64, 66 and 68 are annular and centered on the axis X1. Theshoulder 64 is part of the ring 10. The elements 62, 66 and 68 areseparate from the rings 10 and 20. The washer 68 is mounted within agroove 67 formed within the ring 10, against the shoulder 64. Theelements 62 and 66 are mounted within a housing 61 provided for thispurpose within the ring 10, opposite the shoulder 64.

Alternatively, the sealing means 60 may comprise two removable flangesmounted on opposite sides of the component 1.

The component 1 is non-jointed, in other words it does not constitute aspherical joint. The assembled component 1 has only one degree offreedom, namely the pivotal connection between the rings 10 and 20around the central axis X1. The rings 10 and 20 are freely movable inrelation to one another around the axis X1, but are not freely movableaccording to the other degrees of freedom, in translation and rotation.

The friction surfaces 12 and 22 may be cylindrical.

Alternatively, the surfaces 12 and 22 may be slightly curved. In otherwords, the surfaces 12 and 22 are surfaces of revolution, with acircular section and elliptical or parabolic generatrix. The curvatureof each surface 12 and 22 (considered within a radial plane comprisingthe axis X1) always has a radius that is greater than the radius(considered within a plane transverse to the axis X1) of the frictioninterface 40.

Preferably, at least one of the friction surfaces 12/22/24 comprises asurface treatment or coating having physical properties different from abase material of the corresponding ring 10/20.

More preferably, at least one of the friction surfaces 12/22/24comprises arrangements capable of acting as a reserve of lubricant L.

Still preferably, each friction surface 12/22/24 comprises a surfacetreatment or coating having physical properties different from a basematerial of the ring 10/20; and/or arrangements capable of acting as areserve of lubricant L.

By way of a non-limiting example:

-   -   the rings 10 and 20 are made of steel;    -   the surface 12 is subjected to a nitriding treatment and has an        outer layer 16 of nitrided steel, with a compound layer (oxide        coating) having a thickness of around 20 μm;    -   the surface 12 includes arrangements 18 in the form of circular        section cavities, uniformly distributed around the central axis        X1, capable of acting as a reserve of lubricant L at the        interface 40 between the rings 10 and 20;    -   the surface 22 is coated with an outer layer 26 of DLC type        amorphous carbon having a thickness in the order of 3 μm, with        or without a sub-layer (composed for example of chromium or        chromium nitride); and    -   the surface 24 includes arrangements 28 in the form of circular        grooves, wound around the central axis X1 and regularly spaced        along the central axis X1, capable of acting as a reserve of        lubricant L at the interface between the ring 20 and the axle 2.

The invention makes it possible to provide a hinged component that isresistant, compact and simple to implement. The component 1 comprisingtwo rings 10 and 20 has an improved service life, as compared to acomponent which is composed of a single ring, and having similardimensions and volume.

In the case of a single articulating ring, the wear is typicallylocalized over an angular sector extending over ⅓ of the circumference.In the case of the invention, the inner ring 10 rotates in relation tothe outer ring 20, which greatly increases the potential wear surface,and therefore the service life of the component.

In practice, it can be seen that the friction interface 40 between thetwo rings 10 and 20 takes priority. The opposing friction surfaces 12and 22 perform the function of main wear surfaces. When this interface40 is seized, the inner friction surface 24 of the inner ring 20 incontact with the surface 4 of the axle 2 takes over as a wear surface.

The component 1 has three friction surfaces 12, 22 and 24 forming threewear surfaces, which may be provided with a treatment, a coating and/orarrangements. Thus, the invention provides greater control in the designof the component 1, making it possible to adapt the wear resistancethereof to every application.

The mechanical system comprises four friction surfaces, i.e., the outersurface 4 of the axle 2, and the three surfaces 12, 22 and 24 of thecomponent 1. In comparison with an axle mounted within a single ring,the service life of the mechanical system is greatly improved.

Other embodiments of hinged components 1 according to the invention areshown in FIGS. 6 to 14. Some elements that form part of the component 1are comparable to those of the first embodiment described above, and forthe purposes of simplification bear the same numerical references.

FIGS. 6 to 10 show another mechanical system according to the inventioncomprising a variant of the component 1 and an axle 2 mounted within thecomponent 1. The friction surfaces 12/22/24 are devoid of a surfacetreatment or coating, and arrangements reservoirs of lubricant L. Thesealing means 60 comprise a flange 62 and a shoulder 64 on oppositesides of the interface 40. Thus, the component 1 is simpler and lessexpensive to manufacture than in the first embodiment. Notwithstandingthe absence of a treatment, coating or arrangements, the component 1comprising two rings 10 and 20 has an improved service life, as comparedto a component which is composed of a single ring, and having similardimensions and volume.

FIGS. 11 and 12 show a variant of the hinged component 1 comprisingthree concentric rings 10, 20 and 30, movable in relation to oneanother. The ring 30 is located between the rings 10 and 20. A firstfriction interface 40 is defined between the rings 10 and 30. A secondfriction interface 50 is defined between the rings 20 and 30. Thecomponent 1 has five friction surfaces 12, 22, 24, 32 and 34 formingfive wear surfaces, which may be provided with a treatment, a coatingand/or arrangements.

FIGS. 13 and 14 show a variant of the hinged component 1 comprisingthree concentric rings 10, 20 and 30. The ring 30 is located between therings 10 and 20. The rings 20 and 30 are movable in relation to oneanother, and define a friction interface 50 therebetween. The ring 30 isattached to the ring 10, for example by means of bonding. The ring 30can constitute a winding of fabric strips and a resin comprisingfillers, mixed in such a way as to implement a homogeneous ring, thestrips being crossed over several layers by means of filament winding.The component 1 has three friction surfaces 22, 24 and 32 forming threewear surfaces, which may be provided with a treatment, a coating and/orarrangements.

In practice, the hinged component 1 can be configured differently fromFIGS. 1 to 14 without going beyond the scope of the invention. Moreover,the technical characteristics of the various embodiments mentioned abovecan, as a whole or in part, be combined with each other. Thus, thecomponent 1 can be adapted in terms of cost, functionalities andperformance.

Tables 1-5 below show a series of tests that make it possible to comparetwo reference rings (a single ring receiving an axle) and differentembodiments of the invention.

TABLE 1 Parameters and test conditions Bench Large Oscillation testbench Law of motion Sinusoidal oscillation axis Oscillation amplitude100° Projected pressure 90 MPa Average V over one oscillation 0.0079 m/sAverage PV 0.7 MPa · m/s Grease (type) Extreme Pressure GreaseLubrication Initial only Ring material Steel Axle material 16NC16 Casehardened steel Stoppage criterion COF > 0.35 T° > 120° C. Wear > 0.5 mm

TABLE 2 Pressure build-up at the start of a test Pressure 10 MPa 30 MPa60 MPa 80 MPa 90 MPa Number of 100 100 100 200 500,000 cycles

TABLE 3 Improvements provided on the friction surfaces of the ringsDesignation Improvement characteristics AM1 The inner friction surfacehas arrangements in the form of circular section cavities regularlydistributed around the central axis, acting as a lubricant reservoir.AM2 The inner friction surface receives a nitriding treatment and has acompound layer (oxide coating) having a thickness of around 20 μm. AM3The inner friction surface comprises a polymer lacquer coating. AM4 Theouter friction surface is coated with an outer layer of DLC typeamorphous carbon having a thickness of around 3 μm. AM5 The innerfriction surface has arrangements, in the form of circular grooves woundaround the central axis and regularly spaced along the central axis,acting as a lubricant reservoir. Ring 30 An intermediate ring 30 madefrom a self-lubricating composite is bonded to the inner surface of theouter ring 10.

TABLE 4 Test results-Simple rings Number of cycles Reference AM1 AM2 AM3performed B1 No No No 1,500 B2 Yes Yes Yes 125,000

TABLE 5 Test Results - Components complying with the invention Innerring 20 Outer ring 10 AM4 AM5 Intermediate Reference Inner surface 12Surface Surface ring Number of component 1 AM1 AM2 AM3 22 24 30 cyclesperformed C-BH1 No No No No No No 7,000 C-BH2 Yes Yes Yes No No No350,000 C-BH3 Yes Yes Yes Yes No No 410,000 C-BH4 Yes Yes Yes Yes Yes No530,000 C-BH5 Yes Yes No Yes Yes Yes >500,000

The results of the series of tests allow the following observations tobe made:

-   -   The C-BH1 component completed a number of cycles equivalent to        4.6 times that of the B1 ring.    -   The C-BH2 component completed a number of cycles equivalent to        3.6 times that of the B2 ring.    -   The C-BH3 component completed a number of cycles equivalent to 4        times that of the B2 ring.    -   The C-BH4 component completed a number of cycles equivalent to        4.6 times that of the B2 ring.    -   The test conducted for the C-BH5 component was voluntarily        stopped at 500 000 cycles. The service life thereof is much        higher than that of the B2 ring.

Thus, the invention makes it possible to provide a hinged component 1that is resistant, compact and simple to implement. The component 1comprising several rings has an improved service life, as compared to acomponent which is composed of a single ring, and having similardimensions and volume.

1. Hinged component with one degree of freedom, comprising at least twoconcentric rings, rotatable in relation to one another around a centralaxis, defining a friction interface therebetween, and including: anouter ring having an inner friction surface, and an inner ring having anouter friction surface and an inner friction surface intended to receivea movable member guided by the component in rotation, oscillation and/ortranslation.
 2. Hinged component according to claim 1, wherein thefriction interface between the rings receives a lubricant, and whereinthe component comprises sealing means designed to prevent leakages oflubricant from the friction interface.
 3. Hinged component according toclaim 1, wherein the hinged component comprises elements limiting theaxial and angular displacement of the inner ring in relation to theouter ring.
 4. Hinged component according to claim 1, wherein at leastone of the friction surfaces comprises a surface treatment or coatinghaving physical properties different from a base material of the ring.5. Hinged component according to claim 1, wherein at least one of thefriction surfaces comprises arrangements capable of serving as a reserveof lubricant.
 6. Hinged component according to claim 1, wherein eachfriction surface comprises a surface treatment or coating havingphysical properties different from a base material of the ring and/orarrangements capable of serving as a reserve of lubricant.
 7. Hingedcomponent according to claim 1, wherein the outer ring and the innerring are metallic.
 8. Hinged component according to claim 1, wherein thehinged component comprises only two concentric rings, the frictioninterface being defined directly between the inner friction surface ofthe outer ring and the outer friction surface of the inner ring. 9.Hinged component according to claim 1, wherein the hinged componentcomprises at least three concentric rings.
 10. Mechanical system,comprising a hinged component according to claim 1, and a movable memberguided by the component in rotation, oscillation and/or translation.